Refactorted out the BulkItemPriceEntity in favor of a simpler approach where the bulk pricing information is encoded right in the ItemEntity. It's less flexible in the sense that a given item can only have one bulk rate, but it's simpler too. The multi bulk rate discount support is still in the branch 'multi-bulk-discount-support' if it ever needs to get resurected.
Enhanced the PriceApi to take an optional 'num' parameter so the caller can ask for the per item price of 1 or more of the given items